1. Field of the Invention
This invention relates to a fire-resistant laminate structure and more particularly to horizontally hinged doors for floors, which doors have a high fire rating and which utilize a control system to automatically close the door in a fire.
2. Description of Related Art
The need for fire resistant structures is self-evident and building codes have been passed by government to ensure that public safety is protected. For many buildings and particularly multi-floor buildings it is mandatory to employ fire-resistant materials such as fireproof panels and to design the building to stop or impede the spread of fire and allow time for persons in the building to escape. Partitions, doors, floors, ceilings and the like are required to provide sufficient resistance to the path of a fire and a number of fireproofing techniques to enhance their resistance to fire have been used over the years as is well-known in the art. For convenience, the present description will be directed to horizontal doors for use in floors and, it will be appreciated that the invention can be used in any application where fire-resistance is needed.
Horizontally hinged doors are commonly used for access doors, roof scuttles, automatic fire vents, ceiling access doors, basement doors and for pit, floor and sidewalk doors for access to subterranean locations. In all cases, the doors are used to provide access from one location to another location such as through a floor in a building into a space between the floor and ceiling below. As is apparent, these openings are a safety hazard if a fire breaks out in one section of a building since the fire itself or its harmful byproducts can easily spread throughout the entire building by passing through the above-described openings. Further, such travel can occur irrespective of the fireproof qualities of the building structure components themselves since the fire is not contained. As a result, most fire codes now require that these openings be closed, and that they be closed with materials whose resistance to fire, heat and gases is at least equal to the resistance of the wall, floor, ceiling, or other structural components themselves.
While horizontal doors are known to provide automatic venting in the event of fire as for example where the door provides roof access, it is necessary that horizontal floor doors used in the buildings be automatically closed in the event of fire to contain the fire to a particular floor or location and to prevent the fire from spreading to other floors or areas in the building.
In floor door assemblies, it is highly desirable that a two (2) hour fire rating per ASTM E 119 be achieved to prevent the effect of a fire on the floor below from causing fire damage to the floor above. While the floor door assembly must be capable of being easily opened or closed to provide access, it is essential in the event of fire that the door be automatically closed to contain the fire.
U.S. Pat. No. 4,888,057 describes a structure composed of an aluminum sheet and a multi-layer inorganic intumescent coating. There is no concrete layer. U.S. Pat. No. 4,799,349 describes a steel door with a high density bonded mineral fiber sheet as a core. The bonding material between the mineral sheet and the core is provided by an intumescent binder. There is no concrete layer involved. U.S. Pat. No. 4,699,822 describes an improvement on a prior art method of coating steel with hydraulic cement to protect it from the weakening effects of high heat. No intumescent coating is described. U.S. Pat. Nos. 4,936,064 and 5,305,901 show miscellaneous fireproof items, including a fireproof panel and a fireproof container. U.S. Pat. No. 4,292,538 describes an expanded metal mesh coated with an intumescent coating. There is no concrete involved in this fire proof material. U.S. Pat. No. 4,530,877 issued to Von Bonin et al. on Apr. 19, 1993, describes a building panel employing an intumescent coating. Exemplary intumescent coatings are shown in U.S. Pat. Nos. 4,575,862, 5,035,951; 5,338,349; 4,529,742; 4,380,593; 4,369,064; and 4,367,295. All of the above patents are incorporated herein by reference.
Bearing in mind the problems and deficiencies of the prior art, it is one object of the present invention to provide an improved fire retardant structural article of manufacture.
It is another object of the invention to provide a door assembly such as a horizontal door assembly which automatically closes in a fire or other emergency.
It is a further object of the invention to provide a control system for automatically closing doors or other openings in a fire or other emergency.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.